499) {
// Don't retry other client errors.
throw new ClientError(networkResponse);
} else if (statusCode >= 500 && statusCode <= 599) {
if (request.shouldRetryServerErrors()) {
attemptRetryOnException("server",
request, new ServerError(networkResponse));
} else {
throw new ServerError(networkResponse);
}
} else {
// 3xx? No reason to retry.
throw new ServerError(networkResponse);
}
} else {
attemptRetryOnException("network", request, new NetworkError());
}
}
}
}
上述代码可以看出，真正进行网络请求还是HttpStack.performRequest，在请求结束以后，对返回的状态码进行封装，这里主要说一下304状态码，该状态码，由于只返回header,不返回body，因此body需要从以前缓存的entity中取出body。而HttpStack的两个实现类一个是HttpClientStack,另一个是HurlStack，他们也是直接调用Java自带的http请求方法来得到response。
下面要看的是NetWorkResponse的封装
public NetworkResponse(int statusCode, byte[] data, Map<String, String> headers,
boolean notModified, long networkTimeMs) {
this.statusCode = statusCode;
this.data = data;
this.headers = headers;
this.notModified = notModified;
this.networkTimeMs = networkTimeMs;
}
这就是全部的NetWorkResponse的封装，封装的目的是为了对response进行交付。
ResponseDelivery工作原理
ResponseDelivery是一个接口，其定义了3个方法，2个传递response的重载方法与一个传递error方法
/**
* Parses a response from the network or cache and delivers it.
*/
void postResponse(Request<?> request, Response<?> response);
/**
* Parses a response from the network or cache and delivers it. The provided
* Runnable will be executed after delivery.
*/
void postResponse(Request<?> request, Response<?> response, Runnable runnable);
/**
* Posts an error for the given request.
*/
void postError(Request<?> request, VolleyError error);
其实现类ExecutorDelivery是真正执行的功能类。其内部非常简单，代码如下：
public class ExecutorDelivery implements ResponseDelivery {
/** Used for posting responses, typically to the main thread. */
private final Executor mResponsePoster;
/**
* Creates a new response delivery interface.
* @param handler {@link Handler} to post responses on
*/
public ExecutorDelivery(final Handler handler) {
// Make an Executor that just wraps the handler.
mResponsePoster = new Executor() {
@Override
public void execute(Runnable command) {
handler.post(command);
}
};
}
/**
* Creates a new response delivery interface, mockable version
* for testing.
* @param executor For running delivery tasks
*/
public ExecutorDelivery(Executor executor) {
mResponsePoster = executor;
}
@Override
public void postResponse(Request<?> request, Response<?> response) {
postResponse(request, response, null);
}
@Override
public void postResponse(Request<?> request, Response<?> response, Runnable runnable) {
request.markDelivered();
request.addMarker("post-response");
mResponsePoster.execute(new ResponseDeliveryRunnable(request, response, runnable));
}
@Override
public void postError(Request<?> request, VolleyError error) {
request.addMarker("post-error");
Response<?> response = Response.error(error);
mResponsePoster.execute(new ResponseDeliveryRunnable(request, response, null));
}
/**
* A Runnable used for delivering network responses to a listener on the
* main thread.
*/
@SuppressWarnings("rawtypes")
private class ResponseDeliveryRunnable implements Runnable {
private final Request mRequest;